Isolated childhood growth hormone deficiency: a 30-year experience on final height and a new prediction model

PURPOSE

We aimed to evaluate the near-final height (nFHt) in a large cohort of pediatricpatients with growth hormone deficiency (GHD) and to elaborate a new predictive method of nFHt.

METHODS

We recruited GHD patients diagnosed between 1987 and 2014 and followed-up until nFHt. To predict the values of nFHt, each predictor was run in a univariable spline.

RESULTS

We enrolled 1051 patients. Pre-treatment height was -2.43 SDS, lower than parental height (THt) (-1.09 SDS, p < 0.001). The dose of recombinant human GH (rhGH) was 0.21mg/kg/week at start of treatment. nFHt was -1.08 SDS (height gain 1.27 SDS), higher than pre-treatment height (p < 0.001) and comparable to THt. 1.6% of the patients were shorter than -2 SDS from THt. The rhGH dose at nFHt was 0.19 mg/kg/week, lower than at the start (p < 0.001). The polynomial regression showed that nFHt was affected by gender, THt, age at puberty, height at puberty, age at the end of treatment (F = 325.37, p < 0.0001, R² 87.2%).

CONCLUSION

This large national study shows that GHD children can reach their THt. The rhGH/kg/day dose significantly decreased from the start to the end of the treatment. Our model suggests the importance of a timely diagnosis, possibly before puberty, the beneficial effect of long-term treatment with rhGH, and the key-role of THt. Our prediction model has a very acceptable error compared to the majority of other published studies.

Expanded Newborn Screening in Italy Using Tandem Mass Spectrometry: Two Years of National Experience

Newborn screening (NBS) for inborn errors of metabolism is one of the most advanced tools for secondary prevention in medicine, as it allows early diagnosis and prompt treatment initiation. The expanded newborn screening was introduced in Italy between 2016 and 2017 (Law 167/2016; DM 13 October 2016; DPCM 12-1-2017). A total of 1,586,578 infants born in Italy were screened between January 2017 and December 2020. For this survey, we collected data from 15 Italian screening laboratories, focusing on the metabolic disorders identified by tandem mass spectrometry (MS/MS) based analysis between January 2019 and December 2020. Aminoacidemias were the most common inborn errors in Italy, and an equal percentage was observed in detecting organic acidemias and mitochondrial fatty acids beta-oxidation defects. Second-tier tests are widely used in most laboratories to reduce false positives. For example, second-tier tests for methylmalonic acid and homocysteine considerably improved the screening of CblC without increasing unnecessary recalls. Finally, the newborn screening allowed us to identify conditions that are mainly secondary to a maternal deficiency. We describe the goals reached since the introduction of the screening in Italy by exchanging knowledge and experiences among the laboratories.

Management of Childhood-onset Craniopharyngioma in Italy: A Multicenter, 7-Year Follow-up Study of 145 Patients

CONTEXT

Nationwide data on children diagnosed with craniopharyngioma (CP) are not available in Italy.

OBJECTIVE

This work aimed to identify patients' characteristics, type of surgical approach, complications and recurrences, number of pituitary deficits, and number of patients starting growth hormone (GH) treatment.

METHODS

A retrospective multicenter collection took place of 145 patients aged 0 to 18 years who underwent surgery for CP between 2000 and 2018, and followed up in 17 Italian centers of pediatric endocrinology.

RESULTS

Age at diagnosis was 8.4 ± 4.1 years. Duration of symptoms was 10.8 ± 12.5 months and headache was most frequent (54%), followed by impaired growth (48%) and visual disturbances (44%). Most lesions were suprasellar (85%), and histology was adamantinomatous in all cases but two. Surgical approach was transcranial (TC) in 67.5% of cases and transsphenoidal (TS) in 31.%. The TC approach was prevalent in all age groups. Postsurgery complications occurred in 53% of cases, with water-electrolyte disturbances most frequent. Radiotherapy was used in 39% of cases. All patients but one presented with at least one hormone pituitary deficiency, with thyrotropin deficiency most frequent (98.3%), followed by adrenocorticotropin (96.8%), arginine vasopressin (91.1%), and GH (77.4%). Body mass index (BMI) significantly increased over time. A hypothalamic disturbance was present in 55% of cases. GH therapy was started during follow-up in 112 patients at a mean age of 10.6 years, and 54 developed a recurrence or regrowth of the residual lesion.

CONCLUSION

CP is often diagnosed late in Italy, with TC more frequent than the TS surgical approach. Postsurgery complications were not rare, and hypopituitarism developed almost in all cases. BMI shows a tendency to increase overtime.

Sedentary lifestyle and precocious puberty in girls during the COVID-19 pandemic: an Italian experience

OBJECTIVE

This retrospective study aimed to evaluate children observed for suspected precocious puberty in five Italian centers of Pediatric Endocrinology during the first wave of coronavirus disease 2019 pandemic (March-September 2020), compared to subjects observed in the same period of the previous year.

DESIGN

The study population (490 children) was divided according to the year of observation and final diagnosis: transient thelarche, non-progressive precocious puberty, central precocious puberty (CPP), or early puberty.

RESULTS

Between March and September 2020, 338 subjects were referred for suspected precocious puberty, compared to 152 subjects in the same period of 2019 (+122%). The increase was observed in girls (328 subjects in 2020 vs 140 in 2019, P < 0.05), especially during the second half of the period considered (92 girls from March to May vs 236 girls from June to September); while no difference was observed in boys (10 subjects in 2020 vs 12 in 2019). The percentage of girls with confirmed CPP was higher in 2020, compared to 2019 (135/328 girls (41%) vs 37/140 (26%), P < 0.01). Anthropometric and hormonal parameters in 2019 and 2020 CPP girls were not different; 2020 CPP girls showed more prolonged use of electronic devices and a more sedentary lifestyle both before and during the pandemic, compared to the rest of the 2020 population.

CONCLUSIONS

The present findings corroborate the recently reported association between the complex lifestyle changes related to the lockdown and a higher incidence of CPP in Italian girls.

IGF1 for the diagnosis of growth hormone deficiency in children and adolescents: a reappraisal

A number of studies have evaluated the role of IGF1 measurement in the diagnosis of growth hormone deficiency (GHD). This study aimed to evaluate the accuracy and the best cut-off of IGF1 SDS in the diagnosis of GHD in a large cohort of short children and adolescents. One-hundred and forty-two children and adolescents with GHD ((63 organic/genetic (OGHD), 79 idiopathic (IGHD)) and 658 short non-GHD children (median age 10.4 years) were included in the analysis. The two groups were subdivided according to age (G1 <6, G2 6 <9, G3 9 <12, G4 ≥12) and to pubertal status. Serum IGFI was measured by the same chemiluminescence assay in all samples and expressed as age- and sex-based SDS. Receiver operating characteristic (ROC) analysis was used to evaluate the optimal IGF1 SDS cut-off and the diagnostic accuracy. Median IGF1 SDS was significantly lower in the GHD than in non-GHD patients. The area under the curve (AUC) was 0.69, with the best IGF1 cut-off of -1.5 SDS (sensitivity 67.61%, specificity 62.62%). The AUC was 0.75 for OGHD and 0.63 for IGHD. The accuracy was better in the pubertal (AUC = 0.81) than the prepubertal group (AUC = 0.64). In our cohort, IGF1 measurement has poor accuracy in discriminating GHD from non-GHD. Our findings confirm and reinforce the belief that IGF1 values should not be used alone in the diagnosis of GHD but should be interpreted in combination with other clinical and biochemical parameters.

Adherence to growth hormone (GH) therapy in naïve to treatment GH-deficient children: data of the Italian Cohort from the Easypod Connect Observational Study (ECOS)

BACKGROUND

With the use of non-objective measurement, adherence to growth hormone (GH) therapy has been reported suboptimal in a large proportion of patients, and poor adherence has been shown to affect short-term growth response in patients receiving GH treatment.

OBJECTIVE

The Easypod™ electronic device allows objective measurement of adherence. In this study, we report 3-year prospective adherence data of the Italian cohort of naïve GH deficient (GHD) children extrapolated from the Easypod Connect Observational Study (ECOS) database.

PATIENTS AND METHODS

Seventy-three GHD children naïve to GH treatment were included in the analysis. 22 Italian centers participated in the study.

RESULTS

Mean adherence rate was consistently above 85% across the 3-year observation period. Particularly, mean adherence was 88.5%, 86.6%, and 85.7% after 1, 2 and 3 years, respectively. Mean (± SD) height-SDS increase after the first year was 0.41 (± 0.38).

CONCLUSIONS

The majority of naïve GHD children starting GH treatment with Easypod maintained an adherence rate > 85% up to 3 years. Easypod is a useful tool to follow-up patients' adherence allowing timely intervention to improve optimal treatment for these patients.

SUN-256 Limited Usefulness of Single IGF-I Measurement as a Screening Test for Growth Hormone Deficiency in Children and Adolescents

Introduction: IGF-I measurement has been proposed as a screening tool for the diagnosis of Growth Hormone Deficiency (GHD). However, few studies evaluated the accuracy of IGF-I measurement as a screening test and the results have been controversial. Objective: To evaluate the value of a single IGF-I measurement as screening test in the diagnosis of GHD in short children and adolescents. Patients and Methods: 439 short children (median-IQR age 10.5 (7.1-12.8) y, 273 boys), were included in this retrospective analysis. The patient group consisted of 102 subjects (54 boys) with GHD (peak GH <7.0 μg/L after two provocative tests with Arginine, Insuline Tolerance Test, and Clonidine), 60 of whom had GHD of organic or genetic origin (OGHD) and 42 were idiopathic (IGHD). The 337 subjects with a GH peak ≥7 μg/L and no other recognizable cause for their shortness were considered as controls. All provocative tests were performed between 8.00 and 9.00 am after fasting overnight, without steroid priming. GH and IGF-I were measured by the same chemiluminescence assay in all samples (Immulite, Siemens). Receiver operating characteristic (ROC) analysis was used to evaluate the optimal IGF-I cut-offs and the diagnostic accuracy of IGF-I. The analysis was repeated including only 67 patients with severe GHD (SGHD, peak GH <5.0 μg/L after two provocative tests): 54 organic/genetic (SOGHD) and 18 idiopathic (SIGHD). Results: IGF-I SDS was significantly lower in patients than in controls (-2 (-2.9 - -1.7), -1 (-1.8 - -0.1), respectively, p<0.0001). IGF-I SDS ≥ -2 was found in 42% and 69% of OGHD and IGHD patients, respectively. The Area Under the Curve (AUC, measure of discriminative ability of the test) of IGF-I SDS was 0.73. The IGF-I SDS cut-off of -2 had 50% sensitivity (Se), 80% specificity (Sp), 2.4 likelihood ratio for positive test results (LR+), and 74% diagnostic efficiency (Ef). The best pair of values for Se and Sp was found at IGF-I SDS cut-off of -1.8 (B cut-off, Se 60%, Sp 75%, LR+ 2.3, Ef 71%). For OGHD, AUC was 0.82. For cut-off -2 SDS: Se 60%, Sp 80%, LR+ 3, Ef 80%. B cut-off was -1.9 SDS (Se 68%, Sp 78%, LR+ 3.1, EF 77%). For IGHD, AUC was 0.61. For cut-off -2 SDS: Se 36%, Sp 79%, LR+ 1.7, Ef 77%. B cut-off was -1.4 SDS (Se 52%, Sp 65%, LR+ 1.5, Ef 64%). The results were similar when only patients with SGHD were analysed. Among them, 42% had IGF-I SDS ≥ -2. IGF-I SDS ≥ -2 was found in 41% of SOGHD and in 67% of SIGHD. Conclusions: In our large cohort of short children, IGF-I measurement has shown suboptimal accuracy in discriminating GHD from non-GHD patients. The accuracy is better for patients with organic or genetic GHD. IGF-I values should be interpreted in combination with other clinical and biochemical parameters, and cannot be used alone as a screening tool.

SAT-253 Association between TSH and Cardiovascular Risk Parameters in Obese Children and Adolescents

Introduction: Hyperthyrotropinemia is common in overweight and obese patients and has been hypothesized that high TSH, even within the normal limits, could be associated with an adverse metabolic profile. Objective: Aim of the study was to evaluate the association between TSH and cardiovascular risk parameters in a large group of obese children and adolescents. Patients and Methods: 1402 obese patients (median age 9.7 (2.2-17.8) y, 646 boys) were included in this retrospective analysis. All patients were euthyroid or had mild isolated hyperthyrotropinemia with TSH <10 µU/ml and normal fT4. Waist circumference (WC), systolic and diastolic blood pressure (SP and DP), fasting glycemia, insulin and lipids were measured in all subjects. An Oral Glucose Tolerance Test (OGTT) was also performed (glucose load of 1.75 g/kg of ideal body weight, max 75 g). Insulin resistance was evaluated by Homeostatic Model Assessment (HOMA index, glycemia (mmol/L) x insulin (mU/L) / 22.5). Patients were subdivided into 3 groups according to their TSH level: normal-low TSH (group A, 930 patients, TSH: ≥0,5 - <2.5 µU/ml), normal-high TSH (group B, 432 patients, TSH: ≥2,5 - <4.5µU/ml), mild isolated hyperthyrotropinemia (group C, 40 patients, TSH: ≥4.5 - <10 µU/ml). Results: Median BMI, WC, and fT4 were similar between the 3 groups. The prevalence of patients with high SP, hypertension (high SP and/or DP), and abnormal LDL was higher in patients with hyperthyrotropinemia versus euthyroid patients (p≤0.01), but no differences were found between normal-low and normal-high TSH patients (abnormal SP prevalence: group A 12.6%, group B 14.7%, group C 30.1%; hypertension: group A 14.3%, group B 18.1%, group C 36.1%; abnormal LDL prevalence: group A 14.6%, group B 16.3%, group C 37.5%). Median insulin and HOMA and the prevalence of patients with abnormal HOMA were higher in group C (17 mU/ml, 3,87, and 65%, respectively) than in group A (12.4 mU/ml, 2.64, 39,6%, p≤0.007), and were higher in group B (14 mU/ml, 3,07, 49%, respectively) than in group A (p≤0.001). DP, basal and post-OGTT glycemia, total cholesterol, HDL and triglycerides were not different between the three groups. Conclusions: In our large cohort of obese children and adolescents, increasing TSH was associated with hypertension, insulin resistance and increased LDL, regardless of BMI and fT4 level. These results confirm that TSH, even if in the normal range, could be associated with an adverse metabolic profile. Further studies are needed to define if TSH could be involved in the pathogenesis of cardiovascular diseases in obesity.

Next-Generation Sequencing Identifies Different Genetic Defects in 2 Patients with Primary Adrenal Insufficiency and Gonadotropin-Independent Precocious Puberty

BACKGROUND

The development of gonadotropin-independent (peripheral) precocious puberty in male children with primary adrenal insufficiency (PAI) is consistent with a defect in the genes encoding for the enzymes involved in steroid hormone biosynthesis.

METHODS

Two young boys presented with peripheral precocious puberty followed by PAI. In both patients, the analysis of CYP21A2 gene encoding 21-hydroxylase was normal. As a second step, a targeted next-generation sequencing (NGS) was performed in both patients using a customized panel of congenital endocrine disor ders.

RESULTS

Case 1 had a new homozygous variant in the CYP11B1 gene (c.1121+5G>A). Mutations of this gene cause congenital adrenal hyperplasia due to 11β-hydroxylase deficiency, an essential enzyme in the cortisol biosynthesis pathway. Case 2 showed a new hemizygous mutation in the NR0B1 gene (c.1091T>G), which encodes for DAX1 (dosage-sensitive sex reversal, adrenal hypoplasia congenita [AHC] and critical region on the X chromosome gene 1). NR0B1 mutations cause X-linked AHC and hypogonadotropic hypogonadism. Pathogenicity prediction software defined both mutations as probably damaging.

CONCLUSIONS

Peripheral precocious puberty was the atypical presentation of 2 rare genetic diseases. The use of NGS made the characterization of these 2 cases with similar clinical phenotypes caused by 2 different genetic defects possible.

Influence of Hashimoto Thyroiditis on the Development of Thyroid Nodules and Cancer in Children and Adolescents

It is unclear whether patients with Hashimoto thyroiditis (HT) are predisposed to develop thyroid nodules and/or thyroid cancer. The objective of our study was therefore to assess the prevalence of thyroid nodules and/or cancer in patients with HT and to look for possible prognostic factors. A retrospective survey of 904 children/adolescents with HT (709 females, 195 males) regularly followed in nine Italian centers of pediatric endocrinology was performed. Median period of follow-up was 4.5 years (1.2 to 12.8 years). We evaluated free T4, TSH, thyroid peroxidase antibody (TPOAb), thyroglobulin antibodies, and thyroid ultrasound yearly. One hundred seventy-four nodules were detected, with an annual incidence rate of 3.5%. Ten nodules were malignant (8 papillary and 2 papillary follicular variant), giving a 5.7% prevalence of cancer among patients with nodules. The severity of hypoechogenity at ultrasound, TPOAb, and free T4 serum concentrations were predictive for the appearance of new nodules. Furthermore, a positive correlation was observed between TPOAb titer and the development of thyroid cancer. In conclusion, HT seems to influence the development of thyroid nodules, but not cancer in children and adolescents.

Cardiovascular Risk Factors in Children and Adolescents With Obesity: Sex-Related Differences and Effect of Puberty

Objectives: To evaluate the effect of gender and puberty on cardiovascular risk factors (CVRF) in obese children and adolescents. Methods: One thousand four hundred and nine obese patients [age 9.7 (2.2-17.9) y; 646 Male] were studied. Subjects were stratified according to Tanner pubertal staging and age into prepubertal ≤ and >6 ys (G1 and G2), pubertal stage 2-3 (G3), and pubertal stage 4-5 (G4). Waist circumference (WC), systolic and diastolic blood pressure (SP, DP), fasting plasma glucose, insulin, post Oral Glucose Tolerance Test glucose and insulin, and lipids were evaluated. Insulin resistance was evaluated by HOMA index. Patients with no CVRF were considered metabolically healthy (MHO). Results: The percentage of MHO patients was 59.8% in G1 while was consistently around 30% in the other groups. WC was more frequently abnormal in G2 males. Pubertal progression was associated with a decrease in WC abnormalities. SP was more frequently abnormal in G4 males and pubertal progression was associated with higher prevalence of abnormal SP in males. Pubertal progression was associated with an increase in hypertension rate in both sexes. HOMA was more frequently abnormal in G2 and G3 females. HDL, LDL, and TG were more frequently abnormal in G2 females. Dyslipidemia rate was higher in G2 females. Pubertal progression was associated with higher prevalence of abnormal HDL in males. Conclusions: Sex and pubertal status influence the frequency of abnormalities of CVRF in obese children and adolescents. CVRF are already present in prepubertal age. Identifying patients with higher risk of metabolic complications is important to design targeted and effective prevention strategies.

Reliability of clonidine testing for the diagnosis of growth hormone deficiency in children and adolescents

OBJECTIVE

The diagnosis of growth hormone deficiency (GHD) is currently based on clinical, auxological, biochemical and neuro-radiological investigation. Provocative tests of GH secretion using physiological/pharmacological stimuli are required to confirm GHD. The clonidine test (CT) is widely used to assess GH secretory status. In this retrospective study, we analyzed the reliability of CT and the effect of puberty in a large number of children with short stature who had been evaluated for suspected GHD.

DESIGN AND PATIENTS

Data were collected retrospectively from 327 children and adolescents with short stature (204 boys and 123 girls, median age 10.5 years (IQR 7.90-12.40) followed in four Italian Paediatric Endocrine Units (Cagliari, Genova, Napoli and Roma) between 2005 and 2013.

MEASUREMENTS

All children underwent CT as the first GH stimulation test after exclusion of other known cause of their short stature.

RESULTS

In 73 prepubertal children and 25 pubertal children, the GH peak after CT was <7 μg/L. GHD was confirmed in 87 (37 organic, 50 idiopathic). Six prepubertal and five pubertal patients showed false positive responses. The median BMI-SDS in these children was similar to that of children with GH peak ≥7 μg/L, and none were obese. Overall, the prevalence of false-positive responses was 3.3%. The median (IQR) peak GH after CT was similar between prepubertal and pubertal GHD (3.80 μg/L [1.7-6.00] vs 3.51 μg/L [0.76-5.74]) and non-GHD (13.70 μg/L [10.70-18.40] vs 12.40 μg/L [9.90-19.25]) children.

CONCLUSIONS

Our results show that CT is a reliable and safe GH-releasing agent in both prepubertal and pubertal children.

Thyroid function in children and adolescents with Hashimoto's thyroiditis after l-thyroxine discontinuation

OBJECTIVE

Thyroid function may recover in patients with Hashimoto's thyroiditis (HT).

DESIGN

To investigate thyroid function and the need to resume l-thyroxine treatment after its discontinuation.

SETTING

Nine Italian pediatric endocrinology centers.

PATIENTS

148 children and adolescents (25 m and 123 f) with HT on treatment with l-thyroxine for at least one year.

INTERVENTION AND MAIN OUTCOME MEASURE

Treatment was discontinued in all patients, and serum TSH and fT4 concentrations were measured at the time of treatment discontinuation and then after 2, 6, 12 and 24 months. Therapy with l-thyroxine was re-instituted when TSH rose >10 U/L and/or fT4 was below the normal range. The patients were followed up when TSH concentrations were between 5 and 10 U/L and fT4 was in the normal range.

RESULTS

At baseline, TSH was in the normal range in 139 patients, and was between 5 and 10 U/L in 9 patients. Treatment was re-instituted after 2 months in 37 (25.5%) patients, after 6 months in 13 patients (6.99%), after 12 months in 12 patients (8.6%), and after 24 months in an additional 3 patients (3.1%). At 24 months, 34 patients (34.3%) still required no treatment. TSH concentration >10 U/L at the time of diagnosis was the only predictive factor for the deterioration of thyroid function after l-thyroxine discontinuation.

CONCLUSIONS

This study confirms that not all children with HT need life-long therapy with l-thyroxine, and the discontinuation of treatment in patients with a TSH level <10 U/L at the time of diagnosis should be considered.

Cut-off limits of the peak GH response to stimulation tests for the diagnosis of GH deficiency in children and adolescents: study in patients with organic GHD

OBJECTIVE

The diagnosis of GH deficiency (GHD) in children and adolescents is established when GH concentrations fail to reach an arbitrary cut-off level after at least two provocative tests. The objective of the study was to define the optimal GH cut-offs to provocative tests in children and adolescents.

DESIGN

Retrospective study in 372 subjects who underwent evaluation of GH secretion. GH and IGF-I were measured by chemiluminescence assay in all samples. Receiver operating characteristic (ROC) analysis was used to evaluate the optimal GH cut-offs and the diagnostic accuracy of provocative tests.

METHODS

Seventy four patients with organic GHD (GH peak <10μg/L after two provocative tests) and 298 control subjects (GH response >10μg/L to at least one test) were included in the study. The provocative tests used were arginine, insulin tolerance test (ITT) and clonidine. Diagnostic criteria based on cut-offs identified by ROC analysis (best pair of values for sensitivity and specificity) were evaluated for each test individually and for each test combined with IGF-I SDS.

RESULTS

The optimal GH cut-off for arginine resulted 6.5μg/L, 5.1μg/L for ITT and 6.8μg/L for clonidine. IGF-I SDS has low accuracy in diagnosing GHD (AUC=0.85). The combination of the results of provocative tests with IGF-I concentrations increased the specificity.

CONCLUSIONS

The results of the ROC analysis showed that the cut-off limits which discriminate between normal and GHD are lower than those commonly employed. IGF-I is characterized by low diagnostic accuracy.

Growth hormone treatment in non-growth hormone-deficient children

Until 1985 growth hormone (GH) was obtained from pituitary extracts, and was available in limited amounts only to treat severe growth hormone deficiency (GHD). With the availability of unlimited quantities of GH obtained from recombinant DNA technology, researchers started to explore new modalities to treat GHD children, as well as to treat a number of other non-GHD conditions. Although with some differences between different countries, GH treatment is indicated in children with Turner syndrome, chronic renal insufficiency, Prader-Willi syndrome, deletions/mutations of the SHOX gene, as well as in short children born small for gestational age and with idiopathic short stature. Available data from controlled trials indicate that GH treatment increases adult height in patients with Turner syndrome, in patients with chronic renal insufficiency, and in short children born small for gestational age. Patients with SHOX deficiency seem to respond to treatment similarly to Turner syndrome. GH treatment in children with idiopathic short stature produces a modest mean increase in adult height but the response in the individual patient is unpredictable. Uncontrolled studies indicate that GH treatment may be beneficial also in children with Noonan syndrome. In patients with Prader-Willi syndrome GH treatment normalizes growth and improves body composition and cognitive function. In any indication the response to GH seems correlated to the dose and the duration of treatment. GH treatment is generally safe with no major adverse effects being recorded in any condition.

Correlation between cortisol and components of the metabolic syndrome in obese children and adolescents

BACKGROUND

In obese subjects it has been shown that cortisol (F) contributes to the reduction in insulin sensitivity, suggesting a role in the development of the metabolic syndrome (MS).

AIM

The aim of this retrospective study was to evaluate the relationship between F and components of MS in 1,027 obese children and adolescents.

SUBJECTS AND METHODS

Waist circumference, systolic and diastolic blood pressure (SP, DP), F, serum glucose (Glyc), cholesterol HDL, triglycerides and homeostatic model assessment (HOMA index) were evaluated in all subjects. MS was defined according to the International Diabetes Federation criteria. Accordingly, patients were subdivided into three age groups: 6-10, 10-16 and >16 years.

RESULTS

In univariate regression analysis, F was correlated with Glyc, SP and HOMA in groups 1 and 2, with DP in Group 2. In multivariate regression analysis including age, sex, puberty, BMI-SDS and F as independent variables and one of the component of the MS as the dependent variable, F was a weak predictor of the variability when DP and Glyc were introduced as dependent variables in Group 2 and when SP was introduced as dependent variable both in groups 1 and 2. When patients were subdivided into subgroups according to the IDF criteria, in Group 2 patients with one or more components of the MS had higher F concentrations.

CONCLUSIONS

In this cohort of obese children and adolescents, F was weakly associated with components of the MS. These findings do not support a major role for F in the development of MS.

The role of FTO genotype on eating behavior in obese Sardinian children and adolescents

AIM

We aimed to study the influence of the fat mass and obesity-associated (FTO) gene on eating behavior in 412 obese Sardinian children and adolescents. Genome-wide association studies (GWAS) have identified several susceptibility loci for obesity. Among these, the polymorphisms in the intron 1 of the FTO gene has been found associated to weight gain and obesity in various populations.

METHODS

All obese patients were genotyped for the FTO single nucleotide polimorphysm (SNP) rs9939609. In all subjects we evaluated eating behavior using the Child Eating Behaviour Questionnaire (CEBQ).

RESULTS

We found no differences in eating behavior according to the genotype, either in the entire cohort, or when subjects were subdivided into four different age groups.

CONCLUSIONS

FTO genotype is associated with body mass index but does not influence eating behavior in a selected cohort of obese children from the isolated genetic population of Sardinia.

New aspects of the physiology of the GH-IGF-1 axis

Growth hormone (GH) secretion from the pituitary is regulated by a complex network of CNS and peripheral inputs. Circulating GH binds to its receptor and initiates a cascade of signaling events which involve the JAK2-STAT pathway, the PI3K/Akt pathway and the RAS/MAPK pathway, leading to the transcription of several genes, including insulin-like growth factor 1 (IGF-1), IGFBP3, ALS, and others. Recent findings indicate that nutrition plays an important role in GH secretion and action. Furthermore, data are emerging which suggest that the RAS-MAPK pathway as well as epigenetic regulation of transcription may be important in determining both circulating and locally produced IGF-1.

rs9939609 in the FTO gene is associated with obesity but not with several biochemical parameters in Sardinian obese children

Several studies have reported an association of the intronic single nucleotide polymorphism (SNP) rs9939609 of the fat mass and obesity-associated (FTO) gene with obesity and with a number of obesity-related features. We studied the association of rs9939609 with obesity in 912 obese children and adolescents (426 males and 486 females, mean ± SD age 10.5 ± 3.3 years) and in 543 normal weight subjects. A number of biochemical and clinical parameters was also evaluated in 700 of these patients. In the obese group, mean body mass index standard deviation score (BMI-SDS) was similar between the three genotypes. The A allele was present in 55% of the patients' and in 43% of controls' chromosomes. The distribution of heterozygotes was similar between patients and controls (47%), while the distribution of AA homozygotes was significantly higher in patients (31% vs. 20%). Logistic regression analysis on the genotypes yielded a χ(2) of 35.5 with an odds ratio of 1.6 (CI = 1.3-1.8), P < 1 × 10(-5) . None of the clinical and metabolic parameters tested was associated with the genotype. In conclusion, we have confirmed the strong association between FTO and obesity, and shown that only AA homozygotes are predisposed to develop obesity while TT homozygotes might be protected. Finally, we found no association between rs9939609 and a number of obesity-related abnormalities.

Effect of body mass index on the growth hormone response to clonidine stimulation testing in children with short stature

OBJECTIVES

An inverse relationship has been shown between body mass index (BMI) and the peak growth hormone (GH) response to stimulation in adults and in children with short stature. This relation is observed even within a normal range of BMI. The aim of this study was to investigate the effect of BMI on the GH response to clonidine in a large number of children with short stature.

DESIGN

We conducted a retrospective study on the GH response to clonidine in a single centre.

METHODS

We studied 202 children with short stature (135 M and 67 F) who underwent clonidine testing from 2007 to 2009.

RESULTS

One hundred and twenty-eight patients had a GH peak >10 μg/l. In univariate regression analysis, the peak GH after clonidine was negatively correlated with BMI-standard deviation score (BMI-SDS) and positively correlated with height velocity-SDS and IGF-I-SDS. Only the relationship between peak GH and BMI-SDS remained significant in children with a BMI-SDS from -2 to +2. In the multivariate stepwise regression analysis, BMI-SDS and IGF-I-SDS were the only significant variables in the entire cohort, explaining 19·5% of the variance in peak GH. When only subjects with BMI-SDS between -2·0 and +2·0 were included in the analysis (n = 173), BMI-SDS alone explained 21·4% of the variability in peak GH. The number of patients who failed the clonidine test increased with increasing BMI-SDS.

CONCLUSIONS

BMI affects the GH response to clonidine in children with short stature and should be considered when interpreting the results to the stimulation test.